Every long ride we've done (Trans Lab Hwy-TAT (2 years), and CDR 2012). we've done starting 3rd week in August, finishing in early to mid- Sept. Yes, it's HOT on Eastern portion of TAT and in OK,NV, but little or no rain. CDR of course is cooler due to high altitude most of the way, so Aug/Sept is also ideal. I'd much rather deal with heat vs rain and MUD.